Data translation system and method

ABSTRACT

A data translation system ( 100 ) for performing a non-linear data translation on a digitized AC signal is provided. The non-linear data translation system ( 100 ) includes an input for receiving the digitized AC signal, an output for outputting a non-linearly translated signal, and a processing system ( 104 ) coupled to the input and to the output. The processing system ( 104 ) is configured to receive the digitized AC signal, non-linearly translate the digitized AC signal using a predetermined transfer function to create the non-linearly translated signal, and transfer the non-linearly translated signal to the output.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a data translation system and method,and more particularly, to a data translation system and method forperforming a non-linear data translation.

2. Statement of the Problem

An optocoupler is a device that communicates signals from a first deviceto a second device using light. The optocoupler therefore can be used toprovide electrical isolation, such as between specific components orcircuits. The electrical isolation advantageously can be used to preventa component or circuit from drawing excessive electrical current. Theelectrical isolation can further be used to prevent a short-circuit orother problem in a device from affecting other devices. Consequently, anoptocoupler is often used for isolating electrical devices and/orelectrical circuits.

One isolation application is employed where a device is located withinan explosive or hazardous environment. An optocoupler can be used toensure that the device does not and cannot draw excessive electricalcurrent and therefore cannot create a spark or cause ignition.

An optocoupler has drawbacks. An optocoupler has a relatively slowswitching speed. As a result, an optocoupler has a limited signalingbandwidth. Further, an optocoupler is a passive device and does notperform any signal transmission control or regulation.

Aspects of the Invention

In one aspect of the invention, a data translation system for performinga non-linear data translation on a digitized AC signal comprises:

an input for receiving the digitized AC signal;

an output for outputting a non-linearly translated signal; and

a processing system coupled to the input and to the output andconfigured to receive the digitized AC signal, non-linearly translatethe digitized AC signal using a predetermined transfer function tocreate the non-linearly translated signal, and transfer the non-linearlytranslated signal to the output.

Preferably, the predetermined transfer function creates the non-linearlytranslated signal with respect to a predetermined reference point.

Preferably, the predetermined transfer function is configured toalternatively compress or amplify digital values of the digitized ACsignal.

Preferably, the predetermined transfer function is configured toalternatively compress or amplify digital values of the digitized ACsignal in relation to a distance from the predetermined reference point.

Preferably, the non-linear data translation substantially preservesphase information in the non-linearly translated signal.

Preferably, the non-linear data translation preserves zero-crossinginformation in the non-linearly translated signal.

Preferably, the non-linear data translation substantially reduces asignal bandwidth of the non-linearly translated signal.

In one aspect of the invention, a data translation method for adigitized AC signal comprises:

receiving the digitized AC signal;

non-linearly translating the digitized AC signal using a predeterminedtransfer function to create a non-linearly translated signal; and

transferring the non-linearly translated signal.

Preferably, the predetermined transfer function creates the non-linearlytranslated signal with respect to a predetermined reference point.

Preferably, the predetermined transfer function is configured toalternatively compress or amplify digital values of the digitized ACsignal.

Preferably, the predetermined transfer function is configured toalternatively compress or amplify digital values of the digitized ACsignal in relation to a distance from the predetermined reference point.

Preferably, the non-linear data translation substantially preservesphase information in the non-linearly translated signal.

Preferably, the non-linear data translation preserves zero-crossinginformation in the non-linearly translated signal.

Preferably, the non-linear data translation substantially reduces asignal bandwidth of the non-linearly translated signal.

In one aspect of the invention, an optocoupler transmission system forcontrolling signal transmission through an optocoupler transmissionmedium comprises:

an optocoupler; and

a controller coupled to the optocoupler and configured to receive atransmit attempt from a first device, determine if a second device isalready transmitting through the optocoupler, determine if receiving thetransmit attempt is outside a deadband period after a power-upoccurrence, and transmit from the first device through the optocouplerif the second device is not transmitting and if the deadband period haselapsed.

Preferably, the controller is further configured to hold off the firstdevice from transmitting through the optocoupler until the second devicehas completed transmission if the second device is already transmitting.

Preferably, the controller being is configured to hold off the firstdevice from transmitting through the optocoupler until the deadbandperiod has elapsed if the transmit attempt is within the deadbandperiod.

Preferably, the optocoupler transmission system includes at least twodevices communicating through the optocoupler.

Preferably, the optocoupler transmission system implements amaster-slave communication scheme.

In one aspect of the invention, a transmission control method forcontrolling signal transmission through an optocoupler transmissionmedium comprises:

receiving a transmit attempt from a first device;

determining if a second device is already transmitting through theoptocoupler transmission medium;

determining if receiving the transmit attempt is outside a deadbandperiod after a power-up occurrence; and

transmitting from the first device through the optocoupler transmissionmedium if the second device is not transmitting and if the deadbandperiod has elapsed.

Preferably, the method further comprises holding off the first devicefrom transmitting through the optocoupler transmission medium until thesecond device has completed transmission if the second device is alreadytransmitting.

Preferably, the method further comprises holding off the first devicefrom transmitting through the optocoupler transmission medium until thedeadband period has elapsed if the transmit attempt is within thedeadband period.

Preferably, the optocoupler transmission medium includes at least twodevices communicating through the optocoupler transmission medium.

Preferably, the method implements a master-slave communication scheme.

DESCRIPTION OF THE DRAWINGS

The same reference number represents the same element on all drawings.It should be understood that the drawings are not necessarily to scale.

FIG. 1 shows a bus loop system according to an embodiment of theinvention.

FIG. 2 shows greater detail of an isolation feature of the signalprocessor according to an embodiment of the invention.

FIG. 3 shows a translation system for performing a data translation on adigitized AC signal according to an embodiment of the invention.

FIG. 4 shows a transfer function according to an embodiment of theinvention.

FIG. 5 shows an AC signal at the input of the translation system.

FIG. 6 shows the digitized AC signal after non-linear data translationaccording to the invention.

FIG. 7 is a flowchart of a data translation method for a digitized ACsignal according to an embodiment of the invention.

FIG. 8 shows a prior art optocoupler communication system that performsduplex communications through an optocoupler transmission medium betweendevice A and device B.

FIG. 9 shows an optocoupler communication system according to anembodiment of the invention.

FIG. 10 shows further detail of the optocoupler communication systemaccording to an embodiment of the invention.

FIG. 11 is a flowchart of a transmission control method for controllingsignal transmission through an optocoupler transmission medium accordingto an embodiment of the invention.

DETAILED DESCRIPTION OF THE INVENTION

FIGS. 1-11 and the following description depict specific examples toteach those skilled in the art how to make and use the best mode of theinvention. For the purpose of teaching inventive principles, someconventional aspects have been simplified or omitted. Those skilled inthe art will appreciate variations from these examples that fall withinthe scope of the invention. Those skilled in the art will appreciatethat the features described below can be combined in various ways toform multiple variations of the invention. As a result, the invention isnot limited to the specific examples described below, but only by theclaims and their equivalents.

FIG. 1 shows a bus loop system 100 according to an embodiment of theinvention. The bus loop 100 includes a host system 1, a bus loop 4, abus instrument 10, and a signal processor 30 coupling the bus instrument10 to the bus loop 4. The host system 1 generates a loop voltage Y_(L)and a loop current I_(L) over the bus loop 4. The host system 1 maycomprise a central control unit, a CPU, or some other processing systemused to process the signals received over the bus loop 4. According toone embodiment of the invention, the bus loop 4 comprises a two-wire busloop 4. However, it should be understood that the bus loop 4 does nothave to comprise a two-wire bus loop.

The bus instrument 10 can include any manner of sensor or meter, such asa flow meter. In embodiments where the bus instrument 10 includes a flowmeter, the flow meter may comprise a vibratory flow meter, such as aCoriolis flow meter or a densitometer. As shown in FIG. 1, the businstrument 10 includes a sensor 13 and bus instrument electronics 20.The bus instrument electronics 20 may comprise any manner of CPU,processing system, or micro-processing system. According to anembodiment of the invention, the sensor 13 is configured to generatefirst analog signals and input the first analog signals to the businstrument electronics 20. The bus instrument electronics 20 cangenerate second analog signals that are in the form of a variable loopcurrent I_(L) flowing in the bus loop 4. The bus instrument 10 can beconfigured to draw a predetermined or limited amount of power when inuse with the two-wire bus 4. Because of the measurement communicationprotocol and the power limitations built into the bus loop system 100,the bus instrument 10 may be isolated from the two-wire bus loop 4 usinga signal processor 30. In some embodiments, the signal processor 30 cancomprise an intrinsically safe (I.S.) barrier (dashed line).

The isolation limits the electrical power that the bus instrument 10 candraw from the two-wire bus loop 4 and the host system 1. The isolationprevents damage to the two-wire bus loop 4 and the host system 1 uponthe event of catastrophic failure of the bus instrument 10. In addition,the isolation limits electrical power transfer through the I.S. barrierin order to eliminate an explosion hazard and prevent ignition of anyexplosive or flammable materials in the environment of the businstrument 10.

FIG. 2 shows greater details of an isolation feature of the signalprocessor 30 according to an embodiment of the invention. The signalprocessor is shown as receiving a first analog signal from the businstrument 10. However, it should be understood that the first analogsignal does not have to originate from the bus instrument 10, butrather, the signal processor 30 may be utilized in other environmentswhere analog signal processing is required. The analog signal receivedfrom bus instrument 10 over leads 220 are received by an analog todigital converter 240 where the signals are digitized. According to oneembodiment of the invention, the analog-to-digital converter 240comprises a delta sigma converter, which converts the analog signal intoa serial bit stream. However, it should be understood that otheranalog-to-digital converters may be used and the particularanalog-to-digital converter used should not limit the scope of theinvention.

According to an embodiment of the invention, the signal processor 30includes an optocoupler 115 that is connected between the two-wire busloop 4 and the analog-to-digital converter 240. The optocoupler 115 mayalso be referred to as an opto-isolator, optical coupler, orphotocoupler. The optocoupler 115 electrically isolates the businstrument 10 from the host system 1. Consequently, the bus instrument10 cannot short out the two-wire bus loop 4. Furthermore, catastrophicfailure of the bus instrument 10 cannot draw excessive current from thehost system 1. The optocoupler 115 comprises a transmitter light source122 and a receiver light source 123. The transmitter and receiver lightsources 122, 123 can comprise any manner of light-reactive electroniccomponents, including laser transmitter and receiver light sources, LEDtransmitter and receiver light sources, LED laser transmitter andreceiver light sources, etc.

The transmitter light source 122 and the receiver light source 123 arecommonly formed adjacent to each other wherein light generated by thetransmitter light source 122 is directly received by the receiver lightsource 123. In other embodiments, the transmitter light source 122 andthe receiver light source 123 are separated by some optical device, suchas a fiber optic cable, for example. In some embodiments, the twocomponents are formed into a single package as shown in FIG. 2. However,it should be understood that in other embodiments the transmitter lightsource 122 and the receiver light source 123 may comprise separatecomponents.

The transmitter light source 122 generates a light-encoded signal thatcomprises a conversion of electrical current into emitted light. Thereceiver light source 123 receives the light-encoded signal and convertsthe received light back into an electrical signal that is substantiallyidentical to the original electrical signal at the transmitter lightsource 122. The optocoupler 115 is therefore well suited fortransferring digital signals.

In the embodiment shown in FIG. 2, the bus instrument 10 generates afirst analog signal, which is sent to the analog-to-digital converter240. The analog-to-digital converter 240 outputs a digital signal. Thedigital signal is received by the transmitter light source 122 and sentto the receiver light source 123. The receiver light source 123 can thentransmit the received signal to a signal conditioner 250.

The signal conditioner 250 can process the digital signals, which may bein the form of a serial bit stream, for example and convert the digitalsignal into a scaled pulse width modulation (PWM) signal. The PWM signalcan then be converted into a second analog signal and output to the busloop 4.

FIG. 3 shows a translation system 100 for performing a non-linear datatranslation on a digitized AC signal according to an embodiment of theinvention. The translation system 100 includes one or more inputs 101and one or more outputs 102. The translation system 100 receives thedigitized AC signal at the input 101 and outputs a translated signal atthe output 102. The translated signal can be translated into a form thatis more efficient and usable for transmission over a transmissionmedium, such as transmission through the optocoupler 115, for example.However, other transmission media are contemplated and are within thescope of the description and claims.

The translation system 100 is configured to receive the digitized ACsignal, non-linearly translate the digitized AC signal using apredetermined transfer function to create a translated signal portion,and transfer the translated signal portion. The translation system 100can translate the digitized AC signal with respect to a predeterminedreference point. The translation system 100 can translate the digitizedAC signal with respect to a distance from the predetermined referencepoint, such as a vertical distance (i.e., voltage) from the referencepoint.

The translation system 100 can comprise any manner of system, includinga part of the signal processor 30 or other barrier device, ananalog-to-digital (A/D) converter, a processor or microprocessor, apre-processor, etc. Alternatively, in some embodiments the translationsystem 100 can comprise a portion or subsystem of the bus instrument 10.

The translation system 100 can include a processing system 104 andstorage (not shown). The processing system 104 can include a translationroutine 110, a digitized AC signal storage 111 (or storage for at leasta portion of the digitized AC signal, such as a signal portion), and apredetermined transfer function 112. The predetermined transfer function112 is employed to process the digitized AC signal or signal portionthereof and perform the non-linear translation of the signal portion(see discussion below).

FIG. 4 shows a transfer function according to an embodiment of theinvention. The transfer function is non-linear, including bothcompression and amplification. This is shown in the legends above thegraph. Further, in some embodiments the compression and amplificationcan also be non-linear.

The transfer function modifies the digitized AC signal, such as byadjusting specific values or regions, yet without changing the overallshape of the input waveform. The transfer function can comprise amathematical function that translates the digitized AC signal.Alternatively, the transfer function can comprise a series ofcoefficients that are multiplied by the digitized AC signal, essentiallya digital filter. The digitized AC signal is translated in order toimprove the transfer of the digitized AC signal and in order to improvethe efficiency of the transfer. The data translation enhancestransmission by limiting bandwidth. The data translation retains phaseinformation and advantageously retains the phase information whiledecreasing bandwidth. The data translation achieves this by bothcompressing and amplifying the digitized AC signal.

In some embodiments, the digitization can comprise a digitalcommunication protocol that is imposed onto a time-varying AC signal,such as on an analog measurement signal. For example, a HART digitalcommunication protocol can be superimposed on an analog voltage oranalog current signal. The HART protocol in some embodiments can employa Continuous Phase Frequency-Shift Keying (CP-FSK) modulation. However,it should be understood that other communication protocols andmodulations are contemplated and are within the scope of the descriptionand claims.

The transfer function performs amplification on input values that arewithin a specified distance of a reference point. One reference pointcan be an AC signal zero-crossing point, even where the zero-crossingpoint has been shifted above or below a zero voltage level. However,other reference points are contemplated and are within the scope of thedescription and claims.

The amplification can achieve a predetermined gain. The amplificationcan be substantially linear or can be non-linear. In some embodiments,the gain can vary with distance from the reference point. Theamplification around the reference point preserves the zero-crossinginformation. The amplification around the reference point can makezero-crossing discrimination easier.

Conversely, the transfer function performs compression on a signalportion that is more than the predetermined distance from the referencepoint, such as the previously discussed zero-crossing point. Thecompression can be substantially linear or can be non-linear. Thecompression can achieve a predetermined compression. In someembodiments, the compression can vary with a distance from the referencepoint.

FIG. 5 shows an AC signal at the input of the translation system 100.The AC signal comprises a time-varying signal including an amplitude andperiod. The AC signal can be already digitized or alternatively in someembodiments can be digitized by the translation system 100 beforetranslation.

FIG. 6 shows the digitized AC signal after non-linear data translationaccording to the invention. It can be seen from this figure that theoverall peak-to-peak amplitude of the AC signal has been significantlyreduced and compressed without changing the waveform shape. In thisexample, the original AC signal has been compressed from an originalamplitude of about 250 down to an amplitude of about 30. However, at thesame time the amplitude around the reference point, which here is azero-crossing point (even though the amplitude is not zero), has beenamplified. In contrast to the compressed regions where the digitalvalues are about one unit apart vertically, in the amplified regionaround the reference point the digital values are about three unitsapart. This is done so that the reference points in the digitized ACsignal doe not become closer together and harder to discriminate, suchas if the signal regions around the reference point had been compressed.Compressed digital values may be difficult to determine, especially inthe presence of noise superimposed onto the digital values.

The end result is that digital values away from the reference point(such as near the peaks) are relatively close in terms of verticaldistance as a result of the compression. Conversely, the digital valuesaround the reference point are moved vertically apart by theamplification. The result is that the reference points are easier todiscriminate while the overall AC signal requires less overallbandwidth.

FIG. 7 is a flowchart 700 of a data translation method for a digitizedAC signal according to an embodiment of the invention. In step 701, thedigitized AC signal is received.

In step 702, the digitized AC signal is non-linearly translated. Usingthe transfer function, the signal away from a reference point iscompressed (i.e., large digital values are compressed). The compressioncan be of any desired amount and can employ any desired compression. Thecompression of the signal portion in this voltage region operates toreduce the bandwidth of the digitized AC signal and makes thetransmission of the digitized AC signal through the optocoupler moreefficient. Further using the transfer function, the signal close to thereference point is amplified by a predetermined gain (i.e., smalldigital values are amplified). The amplification can be by any desiredgain amount. The amplification preserves the phase information,including the phase information provided by zero crossings of thedigitized AC signal. Further, the amplification can make the zerocrossing points easier to discriminate in the digitized AC signal afterthe digitized AC signal passes through the optocoupler.

In step 703, after the signal portion is compressed/amplified, thenon-linearly translated signal is transferred to the optocoupler fortransmission. After transmission, the phase information can bedetermined from the non-linearly translated signal, including thezero-crossing information. Further, if desired, the compression andamplification can optionally be reversed after the transmission, such asby using a mirror-image (i.e., reverse) transfer function. Subsequently,the method can loop back up to step 701 and iteratively receive andprocess signal portions.

FIG. 8 shows a prior art optocoupler communication system that performsduplex communications through an optocoupler transmission medium betweendevice A and device B. The optocoupler transmission medium includes anoptocoupler and associated wires or other conductors. Two separatetransmission paths are included so that duplex communications (i.e.,communications in both directions) can be performed. In someembodiments, the communications comprise half-duplex communicationswherein only one device can transmit at a time.

The prior art optocoupler communication system has drawbacks. Bothdevice A and device B can attempt to communicate at the same time.Simultaneous communication attempts in a half-duplex communicationsystem will result in a failure of transmission. Further, if atransmission from device A creates an echo back to device A, then deviceA can misinterpret the received echo as a legitimate transmission fromdevice B.

FIG. 9 shows an optocoupler communication system 900 according to anembodiment of the invention. The optocoupler communication system 900includes a controller 920 that regulates communications between device A905 and device B 907 through a transmission medium including theoptocoupler 115. The optocoupler 115 in some embodiments performshalf-duplex (or simplex) communication between devices, wherein only onedevice can transmit at a time.

It should be understood that the controller 920 can be located anywherein the optocoupler communication system 900 and is shown at the right ofthe optocoupler 115 merely for illustration. In some embodiments, thecontroller 920 can comprise a component of the signal processor 30.Further, the controller 920 in some embodiments can comprise a componentof device A 905 or device B 907, wherein the device operates like amaster communication device. At the same time, the other device(s)operates as a slave communication device(s).

The optocoupler communication system 900 is configured to prevent thereception of echoes. Alternatively or in addition, the optocouplercommunication system 900 is configured to prevent more than one devicefrom transmitting at a time.

The optocoupler communication system 900 in some embodiments isconfigured to receive a transmit attempt from a first device A 905,determine if a second device B 907 is already transmitting through theoptocoupler 115, determine if receiving the transmit attempt is outsidea deadband period after a power-up occurrence, and transmit from thefirst device A 905 through the optocoupler 115 if the second device B907 is not transmitting and if the deadband period has elapsed.

FIG. 10 shows further detail of the optocoupler communication system 900according to an embodiment of the invention. In this embodiment, thecontroller 920 and the optocoupler 115 are combined into one device. Thecombined device can include additional capabilities and additionalcircuitry. The controller 920 can include switches 931 and 932 that areswitched by the controller 920 in order to regulate transmission throughthe optocoupler 115. The switches can comprise any manner of switches.

FIG. 11 is a flowchart 1100 of a transmission control method forcontrolling signal transmission through an optocoupler transmissionmedium according to an embodiment of the invention. In step 1101, atransmit attempt is received from a device such as device A. It shouldbe understood that the transmit attempt can be from any device, butdevice A is used in this figure and example for purposes of clarity.

In step 1102, it is determined whether device B is already transmitting.If device B is already transmitting, then the method proceeds to step1103. If device B is not already transmitting, then the method branchesto step 1105.

In step 1103, where device B is already transmitting, device A is heldoff from transmitting. The holding off is done until device B hascompleted transmitting.

In step 1104, the method holds off other transmission attempts until thetransmission from device B is complete. The transmission can comprise atransmission from device B to device A in some embodiments, althoughother devices are contemplated and are within the scope of thedescription and claims.

In step 1105, where device B was not already transmitting, the methodchecks to see if the attempt is outside of a deadband. If the transmitattempt is not outside of the deadband, then the method loops back up tostep 1101 and all transmissions are held off until the deadband periodhas elapsed. If instead the transmit attempt is outside the deadband,then the method proceeds to step 1106.

For some bus instruments, during a power-up phase the instrument maygenerate and put out measurements or other data that are not withinspecifications and should not be transmitted. For this reason, themethod can implement a deadband period for a predetermined time afterpower-up. Signals received during this deadband period can be judgedunreliable and can be ignored. Signals arriving after the deadband hasexpired are judged acceptable.

In step 1106, device B is held off from transmitting. This can includeadditional devices if more that two devices can transmit through theoptocoupler transmission medium.

In step 1107, device A is allowed to transmit.

In step 1108, the method checks to see if device A is done transmitting.If device A is not done transmitting, the method loops back to step1106. If (and when) device A is done transmitting, then the method loopsback up to step 1101 and waits for further transmit attempts.

1. A data translation system (100) for performing a non-linear datatranslation on a digitized AC signal, the translation system (100)comprising: an input for receiving the digitized AC signal; an outputfor outputting a non-linearly translated signal; and a processing system(104) coupled to the input and to the output and configured to receivethe digitized AC signal, non-linearly translate the digitized AC signalusing a predetermined transfer function to create the non-linearlytranslated signal, and transfer the non-linearly translated signal tothe output.
 2. The data translation system (100) of claim 1, wherein thepredetermined transfer function creates the non-linearly translatedsignal with respect to a predetermined reference point.
 3. The datatranslation system (100) of claim 1, wherein the predetermined transferfunction is configured to alternatively compress or amplify digitalvalues of the digitized AC signal.
 4. The data translation system (100)of claim 2, wherein the predetermined transfer function is configured toalternatively compress or amplify digital values of the digitized ACsignal in relation to a distance from the predetermined reference point.5. The data translation system (100) of claim 1, wherein the non-lineardata translation substantially preserves a phase information in thenon-linearly translated signal.
 6. The data translation system (100) ofclaim 1, wherein the non-linear data translation preserves azero-crossing information in the non-linearly translated signal.
 7. Thedata translation system (100) of claim 1, wherein the non-linear datatranslation substantially reduces a signal bandwidth of the non-linearlytranslated signal.
 8. A data translation method for a digitized ACsignal, the method comprising: receiving the digitized AC signal;non-linearly translating the digitized AC signal using a predeterminedtransfer function to create a non-linearly translated signal; andtransferring the non-linearly translated signal.
 9. The method of claim8, wherein the predetermined transfer function creates the non-linearlytranslated signal with respect to a predetermined reference point. 10.The method of claim 8, wherein the predetermined transfer function isconfigured to alternatively compress or amplify digital values of thedigitized AC signal.
 11. The method of claim 9, wherein thepredetermined transfer function is configured to alternatively compressor amplify digital values of the digitized AC signal in relation to adistance from the predetermined reference point.
 12. The method of claim8, wherein the non-linear data translation substantially preserves aphase information in the non-linearly translated signal.
 13. The methodof claim 8, wherein the non-linear data translation preserves azero-crossing information in the non-linearly translated signal.
 14. Themethod of claim 8, wherein the non-linear data translation substantiallyreduces a signal bandwidth of the non-linearly translated signal.
 15. Anoptocoupler transmission system (900) for controlling signaltransmission through an optocoupler transmission medium, the optocouplertransmission system (900) comprising: an optocoupler (115); and acontroller (920) coupled to the optocoupler (115) and configured toreceive a transmit attempt from a first device (905), determine if asecond device (907) is already transmitting through the optocoupler(115), determine if receiving the transmit attempt is outside a deadbandperiod after a power-up occurrence, and transmit from the first device(905) through the optocoupler (115) if the second device (907) is nottransmitting and if the deadband period has elapsed.
 16. The optocouplertransmission system (900) of claim 15, with the controller (920) beingfurther configured to hold off the first device (905) from transmittingthrough the optocoupler (115) until the second device (907) hascompleted transmission if the second device (907) is alreadytransmitting.
 17. The optocoupler transmission system (900) of claim 15,with the controller (920) being further configured to hold off the firstdevice (905) from transmitting through the optocoupler (115) until thedeadband period has elapsed if the transmit attempt is within thedeadband period.
 18. The optocoupler transmission system (900) of claim15, wherein the optocoupler transmission system (900) includes at leasttwo devices (905, 907) communicating through the optocoupler (115). 19.The optocoupler transmission system (900) of claim 15, wherein theoptocoupler transmission system (900) implements a master-slavecommunication scheme.
 20. A transmission control method for controllingsignal transmission through an optocoupler transmission medium, themethod comprising: receiving a transmit attempt from a first device;determining if a second device is already transmitting through theoptocoupler transmission medium; determining if receiving the transmitattempt is outside a deadband period after a power-up occurrence; andtransmitting from the first device through the optocoupler transmissionmedium if the second device is not transmitting and if the deadbandperiod has elapsed.
 21. The method of claim 20, further comprisingholding off the first device from transmitting through the optocouplertransmission medium until the second device has completed transmissionif the second device is already transmitting.
 22. The method of claim20, further comprising holding off the first device from transmittingthrough the optocoupler transmission medium until the deadband periodhas elapsed if the transmit attempt is within the deadband period. 23.The method of claim 20, wherein the optocoupler transmission mediumincludes at least two devices communicating through the optocouplertransmission medium.
 24. The method of claim 20, wherein the methodimplements a master-slave communication scheme.